Engine not getting gas?

gato_gordo(USDA Zone: 10)December 2, 2007

I have a Craftsman GT5000 with the Kohler 25HP engine. I tried to start it yesterday after it has sat for several months. The engine turns over fine, but does not start. When I prime the engine with a little gas it starts up immediately, but stops as soon as the prime runs out. I tried this several times with the same result. Since the engine runs fine when primed, it appears that the problem is the engine is not getting gas from the tank. I disconnected the fuel line downstream of the fuel filter and gas poured out easily so I know that the lines are not blocked. Also, the gas looked fine without any crud in it.

Most likely the carburetor main jet has become clogged with varnish (from stale gasoline evaporation) and/or fuel cutoff solenoid valve plunger has stuck for the same reason. Also possible that the carburetor fuel inlet needle valve has become stuck in the closed position from the same cause. Another defect might be that the fuel pump (if so equipped) has failed or become inoperative (due to stale gasoline varnish) during storage. A quick way to test the fuel pump (if equipped with one) is to disconnect the fuel hose from the carb inlet fitting, place the open end of hose into a catch container and crank the engine. If fuel runs out of hose while cranking, the fuel pump (if equipped) is good. If if fuel pump checks OK, you will need to tackle the varnish problem. Attach a piece of fuel hose 12" long (purchase at auto parts store) to the carb inlet fitting. Tie this hose to an improvized prop so that it remains in the vertical position and will not flop over. Carefully fill this hose with spray carburetor cleaner (from auto parts store) and imediately try to start the engine. If it starts and runs so long as you keep the test hose filled, remove test hose and reconnect the OEM fuel hose to carb. IF IT DOES NOT START, let the cleaner stand in the hose for an hour or so. In the interim, spray a small burst of the same carb cleaner inside the carb throat (just don't get carried away here, too much down the throat and the cleaner could end up in the crankcase oil). After an hour or so from filling the hose with carb cleaner, prime the engine with a small spray of the carb cleaner and try to start the engine. If the hose has drained empty (it went into the carb and your problem may be solved) try filling it up again with carb cleaner and start the engine again. Hopefully you got it running by flowing some carb cleaner into the carb inlet as I described. If it still will not run after this "trick", you will probably need to tear down and manually "de-varnish" the carb internals.

The problem turned out to be the fuel cutoff solenoid valve as suggested by Mownie. After playing with the carb and not getting it to run, I purchased a rebuild kit, tore the thing apart and put it back together. Finally, I did what I should have done at the outset and tested the fuel solenoid valve and found that it was stuck. A few minutes with the carb cleaner and it was working again. After reconnecting the carburetor, everything is running fine.